Libyan Agriculture Research Center Journal International 3 (5): 236-240, 2012 ISSN 2219-4304 © IDOSI Publications, 2012 DOI: 10.5829/idosi.larcji.2012.3.5.1105

Evaluation of Post Emergence on Weed Control, Performance and Profitability of Rice (Oryza sativa) at Lafiagi, Kwara State of Nigeria

Ibrahim Usman

College of Agriculture, Ahmadu Bello University, Samaru, Zaria, Nigeria

Abstract: Field experiments were conducted in 2009 and 2010 wet seasons at Lafiagi, Kwara state in the Northern Guinea Savannah of Nigeria to evaluate the effect of some post emergence herbicides on weed control, performance and profitability of rice. The treatments consisted of four post emergence herbicides (450g pretilachlor + 30g pyribenzoxim, 3600g + 2000g 2, 4-Dichlorophenoxy acetic acid, 40g bisbyribac sodium and 1020g pretilachlor + 1980g propanil), two hoe weeding at 6 and 9 WAS and the unweeded plot. The application rates were based on the manufacturers’ recommendations. The treatments were laid out in a randomized complete block design replicated three times. Data on weed cover score, weed dry matter, crop injury, crop vigour, crop stand and grain yields were collected. Gross margin and cost benefit analysis were employed to determine the profitability of each of the control methods. From the results all the herbicides were similar in their effect on weed control and crop growth. The effect of treatments on rice yield were comparable to hoe weeding and significantly higher than unweeded treatments. The application of 40g/lha 1 of bisbyribac sodium and application of 450g pretilachlor + 30g pyribenzoxim as post emergence herbicides applied at 6 WAS gave the highest gross margin and Cost- benefit ratio over hand weeding respectively and are therefore considered as the best post emergence herbicides in rice among the evaluated herbicides in the study area. There is however the need for continuous evaluation of the herbicides in other to check herbicide resistant.

Key words: Herbicides Rice production Weed control Profitability Cost- benefit

INTRODUCTION domestic rice production through a number of strategies, parts of which is the establishment of rice processing Rice (Oryza sativa) is the staple food for more than factories in Kano, Kwara, Ogun and Benue State with a a half of the world population [1]. The global rice combined installed capacity of 730,000 mt per annum [3]. production is estimated at 454.6 million tonnes annually It is very important to take advantage of the substantial which has an average yield of 4.25 tonnes per hectare [2]. processing capacity available in the country by boosting In Nigeria Rice is cultivated virtually in the entire Northern paddy rice production. Efficient rice production will create Guinea Savannah agro ecological zone. Land under rice employment, increases incomes and reduce poverty. cultivation in Nigeria has increased from 1,609,890 ha in Successful weed control is essential for economic 2005/2006 to 2,012,740 ha in 2009/2010, while production rice production [4]. Weed can reduce rice yield by has also moved from 3,286,500kg ha 1 in 2005/2006 to competing for moisture, nutrients and light during the 4,080,940kg ha 1 in 2009/2010. Average Nigeria consumes growing season. Weed infestation can also interfere with about 24.8kg of rice per year. Rice importation in Nigeria combine operations at harvest and significantly increase has grown from less than 500,000 metric tonnes in 1994 harvesting and drying costs. Weed seeds contamination to 2.1 million metric tonnes in 2011. Between 2008 and of rice grain lower grain quality and may lower the cash 2011, Nigeria spent an average of US$ 2.5 Billion on rice value of the crop. Weed infestation is one the causes of importation. [3] This high level of rice importation may serious yield reduction in rice production worldwide. not be sustainable. Therefore, the Nigeria government at Losses caused by weeds vary from one country to the federal level is refocusing attention on stimulating another, depending on the predominant weed flora and on

Corresponding Author: Ibrahim Usman, College of Agriculture, Ahmadu Bello University, Samaru, Zaria, Nigeria. Tel: +2348034374967. 236 Libyan Agric. Res. Cen. J. Intl., 3 (5): 236-240, 2012 the control methods practiced by farmers. Weed Nigeria. was applied at the rate of 4 liters competition do not occur during the entire cropping per hectare (1.440 kg a.i). After which the plot was left for period. Control of weeds during the critical period of two weeks before the land was ploughed and then competition is important, usually it commence around 2 harrowed to obtain a fine tilth, it was then marked out into weeks after seeding and may continue up to 5-8 weeks. 18 plots with 1.0m spacing between blocks and 0.5.0m Hence early weeding is important to reduce yield losses spacing between plots. The gross and net plot sizes were [5]. Yield loss between 40-100% in upland rice has been was 16.0 m22 (4 x 4) m and 12.0 m (4 x 3) m respectively. reported [5-7]. Rice has been found to perform better Common weed species at the site were identified, under good weed management practices [4]. Weeds are classified and recorded. The treatments consisted of 4 one of the primary factors limiting rice yield in Nigeria. post emergence herbicides; hand weeding at 6 and 9 Hoe weeding is the commonest method adopted in WAS and unwedded check. The treatments were laid out controlling weeds in the study area. The practice is in a randomized complete block design replicated three however expensive, labour intensive and the availability times. Pre-emergence herbicides used was 320g/l of labour is often not reliable particularly at the peak of Oxadiargyl applied a day after planting with knapsack the season. Rice being a closely spaced crop, yield losses sprayer in a spray volume of about 200 liters per ha using could even be caused by hoe weeding through crop a deflector nozzle at a pressure of 2.1kg/m.2. At six weeks injury and stand losses, while some grass weeds which after planting different post emergent herbicides were have close resemblance to the rice crop may escape hand applied which were, 450g Pretilachlor + 30g pyribenzoxim weeding. This necessitates the evaluation of an per ha, 3600g Propanil + 2000g 2,4-D per ha. 40g alternative weed control method that may be more Bisbyribac sodium per ha and 1020g pretilachlor + 1980g effective with less labour requirements. Herbicides, propanil per ha. These rates are based on the when used at recommended rate, offers good weed manufacturer’s recommendations. Hoe weeding was done suppression and increased yield in rice production [8]. at 6 and 9 WAS. The variety used was NERICA –1 which The use of pre-emergence herbicides has been reported to is early maturing. The seed were drilled at the rate 80 kg show some promising results in rice.10 reported that /ha with inter row spacing of 25 cm. Fertilizer was applied application of pre-emergence herbicides produced grain at the rate of 300 kg ha 11 of NPK at 3WAS and 150kg ha- yield of rice that are significantly comparable to two hoe of at 6 WAS. Visual observation was used to assess weeding. Herbicides resistance and crop injury is a major the crop injury score using percentage as the scale Where problem in the use of post emergence herbicides, there is 1% = normal plant growth and 100% = leaf scorching and need to identify selective herbicides for rice so as to obvious stunted or dead plant. Weed weight sample was increase rice production and save foreign exchange spent taken from 0.75m2 quadrant. The sample was cleared free of on importation of rice. Major herbicides available for weed soil and weight fresh and oven dried at 70°c to constant control in rice in Nigeria include. propanil, oxadizon, weight for dry matter determination Weed cover score , oxadiargyl, 2, 4-Dichlorophenoxy acetic acid, was assessed visually and expressed in percentage where bisbyribac sodium, pretilachlor+ pyribenzoxim, propanil + 0% represent no weed cover and 100 % represent 2, 4-Dichlorophenoxy acetic acid and pretilachlor + complete weed cover. Data collected were subjected to propanil, [3], but their use by farmers has been limited analysis of variance, where significant differences existed, because of lack of information on crop injury, efficacy and the Duncan multiple range test was use for mean cost benefit analysis of the herbicides. Therefore the separation. focus of this study is to look at the efficacy and To examine the profitability of the different profitability of each of the herbicides available for rice herbicides, the gross margin analysis and cost benefit farmers and compare it with the farmer’s practice of two analysis was done. The gross margin analysis is the hoe weeding in the study area. difference between the total revenue and the total variable cost i.e. GM= TR-TVC Where GM= Gross margin; TR= MATERIALS AND METHODS Total revenue and TVC= Total variable cost The profitability index, also known as cost- benefits Field experiments were conducted in 2009 and 2010 analysis which measures the rate of return on investment wet seasons at Demonstration Plot of Kwara State was calculated. It gives the amount of profit on any Naira Agricultural Development projects located in Lafiagi invested in each of the herbicides It is expressed as Cost- Kwara state, (latitude 7° 4511 and longitude 2°30 ). Located benefit ratio = GM/ VC where GM= Gross margin Where in the Northern Guinea Savannah of V.C. = variable cost of each of the weed control methods

237 Libyan Agric. Res. Cen. J. Intl., 3 (5): 236-240, 2012

The cost of the inputs and price of the products were treatments including the control did not have any obtained from market survey. The variable cost were that significant effect on crop stand. The effect of post of weeding, chemicals and cost of application, the emergence weed control on Crop growth as evident by revenue was the farm gate price of rice at 50/kg (During the data on Crop vigour and crop injury was not affected the study US$=160 Naira). by the application of herbicides. There were no significance differences among all the treatments on crop RESULT vigour and Crop injury as indicated in Table 3 There was initial yellowing of the whole field few days after Table 2 shows the effect of post emergence application but by the 8th weeks after sowing the herbicides on weed weight in 2009 and 2010 rainy yellowish colour had disappeared. seasons. The weight of grasses, broad leaves and sedges Table 4 shows the effect of post emergence in all the herbicides treatments were statistically at par and herbicides on the yield of rice in 2009 and 2010. The yields are comparable to 2 hoe weeding but significantly lower of rice obtained by application of the various herbicides to the no weeding treatment in both years of were statistically comparable with that of hoe weeding. experimentation. All the herbicide had the same effect on The unweeded plots however, produced significantly grasses, broadleaves and sedges however, their control lower yield as compared to both herbicides and hoe on sedges was not very effective. Sida acuta and weeding. Cyperus species were partially controlled. Table 5 shows the profitability of post emergence Crop vigour score in percentage; where 0 represents herbicides in rice in the study area. The application of dead plants and 100 vigorously growing plants. 40g/ l/ha of bisbyribac sodium and 450g pretilachlor +30g Crop injury in percentage; where o represents normal pyribenzoxim gave the highest gross margin and cost- crop plants growth and 100 leaf scorching and obvious benefit ratio which were statistically similar and stunted or dead plant significantly higher than the use of 1020g pretilachlor Table 3 shows the effect of post emergence +1980g Propanil. The use 3600g propanil +2000g 2, 4-D herbicides on crop stand, crop injury and crop vigour in and 2 hoe weeding at 6 and 9 WAS however gave the 2009 and 2010 rainy seasons. The effect of herbicides lowest gross margin and cost-benefit ratio among the treatment on crop establishment as evident by data on herbicides. The unweeded plot resulted in a loss of 7,975 crop stand was not significant in both years. All the Naira/ ha.

Table 1: Effect of post emergence herbicides on weed control at Harvest Weed cover Total weed Weed cover Total weed Treatments 2009 score (%) cover in % 2010 score (%) cover in% Herbicides rate Grasses Broad leaf Sedges Grasses Broad leaf Sedges 450g pretilachlor +30g pyribenzoxim 20 cc 10 10 40b 20 b10 b 10 40c 3600g propanil +2000g 2,4-D 20 c 10 c 10 40 b 20 b10 b 10 40 c 40g Bisbyribac sodium 20c 10 c 10 40 b 20 b10 b 10 40 c 1020g pretilachlor +1980g Propanil 20 c 10 c 10 40 b 20 b10 b 10 40 c Hoe weeding 25b 15 b 10 50b 25 b15 b 10 50 b No weeding 50a 40 a 10 100 a 50 a40 a 10 100a S.E± 0.89 0.76 0.021 1.45 1.74 0.65 0.02 0.34 Means in the same column followed by unlike letter (s) are significantly different (p=0.05), DMTR. Weed cover score in percentage; where 0 represents no weed and 100 complete weed cover

Table 2: Effect of post emergence herbicides on weed weight at harvest in 2009 and 2010 2009 Weed weight(g) 2010 Weed weight (g) Treatments Grasses Broad leaf Sedges Grasses Broad leaf Sedges 450g pretilachlor +30g pyribenzoxim 1.07 b2.22 b1.14 b1.37 b1.72 b0.55 b 3600g propanil +2000g 2,4-D 1.03 b2.27 b1.10 b1.33 b1.77 b0.11 b 40 gBisbyribac sodium 1.33 b2.74 b1.13 b1.35 b2.24 b0.41 b 1020g pretilachlor +1980g Propanil 1.37 b1.19 b1.15 bb1.67 1.69 b0.41 b Hand weeding 1.5b2.02 b1.14 bb1.80 1.5 b0.41 b No weeding 7a17.9 a7.84 a7.3 a17.4 a6.85 a S.E± 0.69 2.37 0.64 0.99 2.87 1.35 Means in the same column followed by unlike letter (s) are significantly different (p=0.05), DMTR.

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Table 3: Effect of post emergent herbicides on crop stand, crop injury and crop vigour in (%) at 9 WAS in 2009 and 2010 2009 2010 ------Treatments a.i./ha Crop stand Crop injury Crop vigour Crop stand Crop injury Crop vigour 450g pretilachlor +30g pyribenzoxim 100 5 95 100 5 95 3600g propanil +2000g 2,4-D 100 9 91 100 9 91 40g Bisbyribac sodium 100 3 97 100 3 97 10200g pretilachlor +1980g Propanil 100 5 95 100 5 95 Hand weeding 100 10 90 100 10 90 No weeding 100 3 100 100 2 100 S.E± 2.456 1.890 2.0980 2.51 1.790 2.100 Means in the same column followed by unlike letter (s) are significantly different (p=0.05), DMTR.

Table 4: Effect of post emergence herbicides on yield in kg ha 1 of rice in 2009 and 2010 Treatments Yield in 2009 Yield in 2010 Yield in combined analysis 450g pretilachlor +30g pyribenzoxim 4131a3718 a 3925 a 3600g propanil +2000g 2,4-D 4126 a3713 a 3920 a 40g Bisbyribac sodium 4212 a3791 a 4001 a 1020g pretilachlor +1980g Propanil 4129 a3716 a 3923 a Hoe weeding 4231 a3807 a 4019a No weeding (control ) 869bb912 890.5b S.E± 14.96 12.96 13.96 Means in the same column followed by unlike letter (s) are significantly different (p=0.05), DMTR.

Table 5: Profitability of rice production under post emergence herbicides Rate in Variable Other Total Revenue Gross Margin Treatment a.i/ha L/Ha cost cost Naira Variable cost (Yield x price) Naira R-TVC Benefit-cost ratio 450g pretilachlor +30g pyribenzoxim 1.5 22,460 52,500 74,960 196250 121,290 5.4 3600g propanil +2000g 2,4-D 10 31,460 52,500 83,960 196000 112,040 3.6 40 gBisbyribac sodium 0.4 21,800 52,500 74,300 200050 125,750 5.8 1020g pretilachlor +1980g Propanil 6 25,460 52,500 77,960 196150 118,190 4.6 Hoe weeding at 6 and 9 WAS 0 32,460 52,500 84,960 200950 115,990 3.6 No weeding 0 0 52,500 52,500 44525 -7,975 0

DISCUSSION selective on rice thus, they did not affect crop stand, crop vigour and did not cause any injury on rice. Crop The major weeds in the study area includes grasses establishment and growth of rice were not affected and such as Cynodon dactylon (L) pers, Digiteria cilliaris their performance were comparable to the conventional willd, Elusine indica Garten and Dactyloctenium spp ( L) farmers practice of two hoe weeding at 6 and 9 WAS. Beave. Broad leaves such as Solanum nigrum L. S. The yield of rice produced by the use of herbicides were americanum Mill. Ageratum conyziods L. Amaranthums comparable with the farmer’s practices of 2 hoe weeding spinosus L. and and all the herbicides performed similar, which resulted in Acanthospermum hispidum DC. Sedges were few almost the same yield. This agrees with the work of and included Sida acuta and Cyperus spp. The use of the (1;2;3;4 and 5) which shows that herbicides, when use in different herbicides at 6WAS to supplement the pre rice suppresses weed and increase the yield of rice.Gross planting and pre emergence herbicides resulted in margin for the uncontrolled plot resulted in a lost and the effective control of weed and yield that are comparable to cost- benefit ratio cannot be calculated since there was no hoe weeding at 6 and 9 WAS in both years of cost incurred. The application of 40g/ l/ha of bisbyribac experimentation. This shows that these herbicides when sodium and of 450g pretilachlor +30g pyribenzoxim were used at the recommended rate have the ability to control more profitable than the use of 1020g pretilachlor +1980g weeds in rice. It was also found that the herbicides had Propanil. The use of 3600g propanil +2000g 2, 4-D and 2 partial control on sedges; they were not very effective on hoe weeding at 6 and 9 WAS, however gave the lowest Sida acuta and Cyperus species. Weeds that emerged gross margin and cost-benefit ratio as compared to the after application were not controlled. The herbicides were other herbicides. The low profitability recorded in the use

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3600g propanil +2000g 2, 4-D and 2 hoe weeding at 6 and 2. Fazlollah, E.C., B. Hoshang and A. Abbas, 2011. 9 WAS were due to the cost associated with the two Evaluation of traditional, mechanized and chemical control methods. Uncontrolled weed in rice resulted in a weed control methods in rice field Australian Journal loss of about N7, 975when compared with the farmer’s of Crop Science, 5(8): 1007-1013. practices of 2 hoe weeding 3. Ibrahim, U., S.A. Rahman and B.A. Babaji, 2011. Cost –benefit analysis of rice production under weed CONCLUSION control methods in Lafiagi area of Kwara NSUK Journal of Science and Technology, 1(1&2): 40-47. From the results from these trials it can be concluded 4. Ishaya, D.B., S.A. Dadadari and J.A.Y. Shebayan, that the application of 40g/l/ha of Bisbyribac sodium or 2007. Evaluation of herbicides for weed control in 450g pretilachlor +30g pyribenzoxim as post emergence three varieties of upland rice (Oryza sativa L.) in the herbicides applied at 6 WAS to supplement the Nigeria Savannah. Crop Protection, 26: 11490-1495. application of 4l/ha of glyphosate applied as pre planting 5. Akobundu I.O. ,1987. Weed science in the tropics. and the 320g/l/ha Oxadiargyl applied as pre emergence Principle and practice. John wiley and son ltd.Great enhanced rice yield and profitability over hand Britian, pp: 522. weeding. Their application gave higher gross margin and 6. Ahmed, N.U. and K. Moody, 1980. Effect of method cost – benefit ratio and are therefore considered as the of seeding and weed control on weed growth and best post emergence herbicides in rice among the yield of two rice crops grown in sequence. Tropical evaluated herbicides in the study area. There is however Pest Management, 26(3): 303-308. the need for continuous evaluation to prevent herbicide 7. Akobundu, I.O. and A. Ahissou, 1984. Effect of inter resistant over time row spacing and weeding frequency on the performance of selected rice cultivars on ACKNOWLEDGMENT hydromorphic soil of West Africa Crop Protection, 4: 71-71. The authors wish to acknowledge the contribution of 8. Adigun, J.A., S.T.O. Lagoke and I.D. Adekpe, 2000. Kwara States ADP. and Kwara State Fadama for their Efficiency of selected herbicides for weed control in valuable supports and TOCNOC limited for providing the rainfed upland rice in the Nigeria Northern Guinea Chemicals used for this work. Savannah. Agricultural Tropical Et Subtropical, 38(3): 99-104. REFERENCES

1. Ginigaddara, G.A.S. and S.L. Ramanukharaechchi, 2009. Effect of conventional SRI and modified water management on growth, yield and water productivity of direct- seeded and transplanted rice in central Thailand. Australian Journal of Crop Science, 3(5): 278-286.

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